Traffic differentiator systems for network devices and related methods

ABSTRACT

Traffic differentiator systems for network devices and related methods are disclosed that determine difference packets from multiple packet streams. Some embodiments are configured to receive two streams of packets with one stream being a processed version of another stream and then to determine difference packets within a lookup time window that is, for example, associated with a processing time for the second stream to be a processed version of the first stream. Difference packets within a lookup time window can also be determined for packets received within a single combined stream of packets. Difference packets and/or related statistical information is then output for additional processing, as desired. The streams of packets can be associated with ingress and egress packets for a network device, and the difference packets and related statistical information can be used to determine packets that are removed, added, and/or modified by the network device.

TECHNICAL FIELD OF THE INVENTION

This invention relates to network packet communication systems and, moreparticularly, to analyzing differences in network packet communicationstreams.

BACKGROUND

Certain network communication systems utilize network packets fornetwork communications. When packets pass through a network device, suchas a firewall device, there is a possibility that some packets will beblocked or added by the device, while other packets will be modified bythe network device prior to being passed along as egress packets toother network devices. For example, NAT (network address translation),PAT (port address translation), TTL (time-to-live), tunneling, and/orother protocols applied by the network device can cause modifications toingress packets prior to their being transmitted along as egress packetsby the network device.

To assist in troubleshooting, it is desirable to determine which packetsare being removed or modified by a network device and to determine ifnew packets are being generated by the device itself. Typically, thisdifference determination is accomplished by storing all packets enteringa network device, storing all packets leaving a network device, andconducting a post-processing manual or automated comparison of allstored packets. While this technique can be used to determine removed,modified, or added packets, this post-processing technique iscumbersome, time consuming, and provides no real time informationconcerning the operations of the network device.

SUMMARY OF THE INVENTION

Traffic differentiator systems for network devices and related methodsare disclosed. The disclosed embodiments are configured to receive twostreams of packets with one stream being a processed version of anotherstream and then to determine difference packets between the first andsecond streams within a lookup time window where the lookup time window,for example, is associated with a processing time for the second streamto be a processed version of the first stream. Difference packets withina lookup time window can also be determined for packets received withina single combined stream of packets. Difference packets and/or relatedstatistical information is then output for additional processing, asdesired. The streams of packets can be associated with ingress andegress packets for a network device, and the difference packets andrelated statistical information can be used to determine packets thatare removed, added, and/or modified by the network device. Differentfeatures and variations can be implemented, as desired, and relatedsystems and methods can be utilized, as well.

In one embodiment, a traffic differentiator system for network packetsincludes a packet difference processor configured to determinedifference packets within a lookup time window between a first stream ofpackets and a second stream of packets received by the trafficdifferentiator system and at least one output port configured to outputthe difference packets. The second stream of packets represents aprocessed version of the first stream of packets, and the lookup timewindow is associated with a processing time for the second stream to bea processed version of the first stream. And the difference packetsinclude packets within the first stream and not within the second streamand packets within the second stream and not within the first stream.For additional embodiments, the packet difference processor can befurther configured to output statistical information about thedifference packets.

In other embodiments, the traffic differentiator system can furtherinclude at least one input port configured to receive the first streamof packets and at least one additional input port configured to receivethe second stream of packets. In addition, the first and second streamsof packets can be from a single network device. Further, the firststream of packets can include only ingress packets for the networkdevice, and the second stream of packets can include only egress packetsfor the network device. Still further, the difference packets canrepresent at least one of packets removed by the network device, packetsadded by the network device, or packets modified by the network device.Also, the system can include one or more packet filters can beassociated with the input ports and configured to drop or pass packetsbased upon filter rules

In further embodiments, the traffic differentiator system can furtherinclude a packet signature generator associated with each input port andconfigured to generate signatures for packets received at the inputport, and a signature table associated with each input port andconfigured to store the signatures, the signature tables beingconfigured to store signatures for the lookup time window. In addition,the packet difference processor can be further configured to perform foreach input port at least one lookup between signatures generated for thepackets received at that input port and the signature table associatedwith at least one other input port and to drop packets where matches arefound. Further, the packet difference processor can be configured toperform two lookups associated with each input port, and wherein apacket buffer stores packets between the two lookups. Still further, thepacket difference processor can perform one lookup associated with eachinput port, and a packet buffer can store packets before the lookup. Forother embodiments, the input ports can be configured to receive ingresspackets or egress packets but not both; the packet difference processorcan be configured to perform one lookup associated with each input port;and a packet buffer can store packets for each input port configured toreceive ingress packets.

In still further embodiments, the first stream of packet can includeonly ingress packets associated with a network device, and the secondpacket stream can include only egress packets associated with thenetwork device. In addition, the packet difference processor can beconfigured to receive a combined packet stream including the firststream of ingress packets and the second stream of egress packets.Further, the traffic differentiator system can further include an inputport configured to receive the combined packet stream. Still further,the traffic differentiator system can further include a packet signaturegenerator configured to generate signatures for packets received at theinput port and a signature table configured to store signatures for thelookup time window. The packet difference processor can also beconfigured to perform two lookups associated with the input port and todrop packets where matches are found, and a packet buffer can storepackets between the two lookups. For other embodiments, the trafficdifferentiator system can further include one or more packet filtersassociated with the input port and configured to drop or pass packetsbased upon filter rules.

In another embodiment, the method for generating difference packetsbetween streams of network packets includes determining differencepackets within a lookup time window between a first stream of packetsand a second stream of packets received by a traffic differentiatorsystem and outputting the difference packets. The second stream ofpackets represents a processed version of the first stream of packets.The lookup time window is associated with a processing time for thesecond stream to be a processed version of the first stream. And thedifference packets include packets within the first stream and notwithin the second stream and packets within the second stream and notwithin the first stream. In further embodiments, the method can includeoutputting statistical information about the difference packets.

In other embodiments, the method includes receiving the first stream ofpackets with at least one input port for the packet differentiatorsystem and receiving the second stream of packets with at least oneadditional input port for the packet differentiator system. In addition,the first and second streams of packets can be received from a singlenetwork device. Further, the first stream of packets can include onlyingress packets for the network device, and the second stream of packetscan include only egress packets for the network device. Still further,the difference packets can represent at least one of packets removed bythe network device, packets added by the network device, or packetsmodified by the network device. Also, the method can include applyingone or more packet filters to drop or pass packets based upon filterrules.

In further embodiments, the determining step can include generatingsignatures for packets received at the input ports, storing thesignatures for the lookup time window, and comparing signatures todetermine difference packets. In addition, the method can includeperforming for each input port at least one lookup between signaturesgenerated for the packets received at that input port and signaturesstored for at least one other input port and dropping packets wherematches are found. Further, two lookups can be performed for each inputport, and the method can include storing packets between the twolookups. Still further, one lookup can be performed for each input port,and the method can further include storing packets before the lookup.For other embodiments, the input ports can be configured to receiveingress packets or egress packets but not both; a lookup can beperformed at each input port for each other input port; and the methodcan further include storing packets for each input port receivingingress packets.

In still further embodiments, the first stream of packet can includeonly ingress packets associated a network device, and the second packetstreams can include only egress packets associated with the networkdevice. In addition, the first stream of ingress packets and the secondstream of egress packets can be combined to form a combined packetstream. Further, the method can include receiving the combined packetstream at an input port for the packet differentiator system. Stillfurther, the determining step can include generating signatures forpackets received at the input port, storing the signatures for thelookup time window, and comparing signatures to determine differencepackets. The method can also include performing two lookups betweensignatures generated for the packets received at the input port andstored signatures and dropping packets where matches are found. Forother embodiments, the method can further include applying one or morepacket filters to drop or pass packets based upon filter rules.

DESCRIPTION OF THE DRAWINGS

It is noted that the appended drawings illustrate only exampleembodiments of the invention and are, therefore, not to be consideredlimiting of its scope, for the invention may admit to other equallyeffective embodiments.

FIG. 1 is a block diagram of an example embodiment for a trafficdifferentiator system configured to receive ingress/egress packets frommultiple ports for a network device.

FIG. 2 is a representative timing diagram of an example embodiment forprocessing ingress/egress packets received from the network device usinga single lookup operation per port and an extended lookup time window.

FIG. 3 is a representative timing diagram of an example embodiment forprocessing ingress/egress packets received from the network device usingtwo lookup operations per port and a lookup time window.

FIG. 4A is a block diagram of an example embodiment for a packetdifference processor that is configured to determine differences betweeningress/egress packets received at two ports using two lookup operationsand a lookup time window.

FIG. 4B is a block diagram of an example embodiment for a packetdifference processor that is configured to determine differences betweeningress/egress packets received at two ports using one lookup operationand an extended lookup time window.

FIG. 5 is a block diagram of an example embodiment for packet differenceprocessor where the ports are configured to receive only ingress packetsor only egress packets.

FIG. 6 is a block diagram of an example embodiment for using a trafficdifferentiator system to determine differences between a plurality ofingress ports and a plurality of egress ports for a network device.

FIG. 7 is a block diagram of an example embodiment where two ingressports and two egress ports are being processed within a packetdifference processor for a traffic differentiator system.

FIG. 8 is a block diagram of an example embodiment where ingress/egressstreams from multiple ports are combined and then provided to an inputport for a traffic differentiator system.

FIG. 9 is a block diagram of an example embodiment for processing acombined packet stream with a packet difference processor for a trafficdifferentiator system.

DETAILED DESCRIPTION OF THE INVENTION

Traffic differentiator systems for network devices and related methodsare disclosed. The disclosed embodiments are configured to receive twostreams of packets with one stream being a processed version of anotherstream and then to determine difference packets between the first andsecond streams within a lookup time window where the lookup time window,for example, is associated with a processing time for the second streamto be a processed version of the first stream. Difference packets withina lookup time window can also be determined for packets received withina single combined stream of packets. Difference packets and/or relatedstatistical information is then output for additional processing, asdesired. The streams of packets can be associated with ingress andegress packets for a network device, and the difference packets andrelated statistical information can be used to determine packets thatare removed, added, and/or modified by the network device. Differentfeatures and variations can be implemented, as desired, and relatedsystems and methods can be utilized, as well.

The disclosed embodiments determine differences between ingress/egresspacket streams and related information by comparing two or moredifferent packet streams for a network device and forwarding thedifference packets that are present in only one of the streams. Thisdifference determination helps to uncover packets that have beenremoved, modified, or added by a network device. This differencedetermination can also be applied to packets received within a singlecombined packet stream. Further, there is no requirement that the packetstream(s) received and processed by the disclosed embodiments includeordered packets and/or ordered packet streams such as typically requiredwhere synchronization of two packet streams is being performed. Packetfilters can also be utilized by the disclosed embodiments to maskcertain packets from this difference processing that are added by thenetwork device, such as TCP ACK (transmission control protocolacknowledge) packets, that are not relevant to the difference analysisultimately being conducted on the difference packets. Further, thetraffic differentiator embodiments can be configured to outputstatistical or other information (e.g., from packet contents) aboutdifference packets (e.g., removed, modified or added packets) inaddition to outputting the difference packets themselves, and thedifference packets and related statistical information can be output toa specified port on the traffic differentiator system for furtheranalysis by an external network monitoring tool. Still further, thetraffic differentiator systems and methods described herein can be usedto determine differences between one or more ingress packet streams andone or more egress packet streams for a network device. As such,difference packets and related information can be output by thedisclosed embodiments and used to analyze real-time operations of a widevariety of network devices (e.g., firewalls, load balancers, routers,switches, and/or other network elements).

FIG. 1 is a block diagram of an example embodiment 100 for a trafficdifferentiator system 112 configured to receive ingress/egress packetsfrom multiple ports for a network device 102. The network device 102 isconfigured to receive ingress packets associated within one or moreports and to output processed versions of these packets as egresspackets on one or more ports using a packet processor 103. The ports forthe network device 102 can be ports configured to receive only ingresspackets, only egress packets, or both ingress and egress packets. Assuch, the packet streams 108 and 110 received with respect to ports forthe network device 102 can also include ingress only packets, egressonly packets, or both ingress and egress packets. It is noted that ifthe packet streams 108/110 include both ingress and egress packets,these packets can be tagged with additional information to facilitate adetermination of whether a difference packet was added, modified, ordeleted by a network device 102. If no additional tagging information isused to determine if packets are ingress or egress packets, adetermination may only be able to be made that a packet is a differencepacket without being able to determine whether this difference packetrepresents an added packet, a modified packet, or a dropped packet.

The traffic differentiator system 112 is configured to receive at afirst port 104 copies of the ingress/egress packets 108 and to receiveat a second port 106 copies of the ingress/egress packets 110. Thetraffic differentiator system 112 determines differences between ingresspackets and egress packets using the packet difference processor 120. Asdescribed in more detail below, a lookup time window 114 is used todetermine a timing window within which the packet difference processor120 looks for packet differences, and this lookup time window 114 can beassociated with the processing time for the packet processor 103 aspackets move through the network device 102. The results of thisdifference processing can include, for example, determining packets thatare removed by the network device 102, packets that are added by thenetwork device 102, packets that are modified by network device 102,and/or other desired difference results or statistical information. Thetraffic differentiator system 112 can be configured to outputinformation associated with the difference processing, such asdifference packets 122 (e.g., removed, added, or modified packets)and/or other information 124 related to the difference processing anddifference packets.

It is noted that for embodiment 100, it is assumed that the first andsecond ports 104/106 receive both ingress and egress packets. Further,it is assumed that ingress packets received at the first port 104 areintended to be received as egress packets at the second port 106.Similarly, it is assumed that ingress packets are intended to bereceived at the second port 106 are received as egress packets at thefirst port 104. The traffic differentiator system 112 is configured todetermine the difference between packets received at the first andsecond ports 104/106. Further, where the ingress or egress type of thepackets are known, the traffic differentiator system 112 can beconfigured to output removed packets separately from added/modifiedpackets. In particular, ingress packets received at the first port 104and not received as egress packets at the second port 106 are deemed tobe packets removed by the network device 102. Egress packets received atthe second port 106 and not received as ingress packets at the firstport 104 are deemed to be packets added or modified by the networkdevice 102. Similarly, ingress packets received at the second port 106and not received as egress packets at the first port 104 are deemed tobe packets removed by the network device 102. Egress packets received atthe first port 104 and not received as ingress packets at the secondport 106 are deemed to be packets added or modified by the networkdevice 102. As such, the traffic differentiator system can outputdifference packets 122 as well as other desired information 124 and canmore particularly output removed packets and added/modified packetswhere the ingress/egress packet type is known for received packets.

FIG. 2 is a representative timing diagram of an example embodiment 200for processing ingress/egress packets received from the network device102 using one lookup operation per port and an extended lookup timewindow 204. For embodiment 200, it is assumed that each port 104/106 isconfigured to receive both ingress and egress packets from ports for thenetwork device 102. As described herein, the traffic differentiatorsystem 112 uses a lookup time window (W) 114 to facilitate thedifference processing of ingress and egress packets, and this lookuptime window 114 can be associated with the processing time for thepacket processor 103 for the network device 102 as packets move throughthe network device 102.

First, assume a packet (PACKETA) 202 is an ingress packet associatedwith the first port (PORT1) 104 and received by the trafficdifferentiator system 112 at time T_(A). As an ingress packet receivedat the first port 104, a related egress packet (PACKETB) 212 should bereceived at the second port (PORT2) 106 at time T_(B). Time T_(B) issome time delay (X) after time T_(A) where the time delay (X) isassociated with the processing delay as the packet travels through thenetwork device 102. To account for this time delay (X), the lookup timewindow (W) 114 is used to delay a lookup operation 206 performed tocompare the ingress packet (PACKETA) 202 received at the first port 104with packets received at the second port 106, such as the packet(PACKETB) 212. The lookup time window (W) 114 is selected so as to begreater than or equal to the processing time delay (e.g., W≧X). Thelookup operation 206 is configured to determine whether or not theingress packet (PACKETA) 202 has been received as an egress packet(PACKETB) 212 at the second port 106.

Second, assume packet (PACKETB) 212 is an egress packet associated withthe second port (PORT2) 106. This egress packet (PACKETB) 212 can againbe assumed to have been received at time T_(B) by the packetdifferentiator system 112. As an egress packet received at the secondport 106, a related ingress packet (PACKETA) 202 should have beenreceived some time delay (X) earlier at time T_(A) at the first port104, where this time delay (X) is again associated with the processingdelay through the network device 102. A lookup time window (W) 114 isagain applied before performing a lookup operation 216 to compare theegress packet (PACKETB) 212 received at the second port 106 with packetsreceived at the first port 104, such as the packet (PACKETA) 202. Thelookup operation 216 is configured to determine whether or not theegress packet (PACKETB) 212 was previously received as an ingress packet(PACKETA) 202 at the first port 104. The extended lookup time window 204is needed, as well, because the packet (PACKETA) 202 could otherwisealready fall outside the lookup time window 114 when the lookupoperation 216 is performed.

For embodiment 200, therefore, because it is not known whether packets202/212 received with respect to ports 104/106 will be ingress or egresspackets, the packets are stored for the length of the lookup time window(W) 114 as well as an additional extended lookup window (W) 204, aswell. By storing received packets for two lookup windows (2×W) includingthe lookup time window (W) 114 and the extend lookup time window (W)204, a single lookup operation 206/216 can be used with respect to eachof the ports 104/106 to determine differences between ingress/egresspackets received at the first port 104 and ingress/egress packetsreceived at the second port 106.

FIG. 3 is a representative timing diagram of an example embodiment 300for processing ingress/egress packets received from the ports 104/106using two lookup operations for each port and lookup time window (W)114. For embodiment 300, the traffic differentiator system 112 againuses a lookup window (W) 114 to facilitate the difference processing ofingress and egress packets but does not use the extended lookup timewindow (W) 204. It is initially noted that as with embodiment 200, eachport 104/106 is assumed to receive both ingress and egress packetsassociated with ports for the network device 102, and embodiment 300 isconfigured to handle both ingress/egress conditions at each port.

First, again assume a packet (PACKETA) 202 is an ingress packetassociated with the first port (PORT1) 104 and received by the trafficdifferentiator system 112 at time T_(A). As an ingress packet receivedat the first port 104, a related egress packet (PACKETB) 212 should bereceived at the second port (PORT2) 106 at time T_(B). Time T_(B) issome time delay (X) after time T_(A) where the time delay (X) is againassociated with the processing delay as the packet travels through thenetwork device 102. To account for this time delay (X), a lookup timewindow (W) 114 is again used to delay a lookup operation 206 performedto compare the ingress packet (PACKETA) 202 received at the first port104 with packets received at the second port 106, such as the packet(PACKETB) 212. The lookup time window (W) 114 is selected so as to begreater than or equal to the time delay (X). The lookup operation 206 isconfigured to determine whether or not the ingress packet (PACKETA) 202has been received as an egress packet (PACKETB) 212 at the second port106. In contrast with embodiment 200 and as described in more detailbelow, an additional lookup operation 302 is also performed when thepacket (PACKETA) 202 is received for conditions where the receivedpacket is an egress packet.

Second, again assume packet (PACKETB) 212 is an egress packet associatedwith the second port (PORT2) 106 that is received at time T_(B) by thepacket differentiator system 112. As an egress packet received at thesecond port 106, a related ingress packet (PACKETA) 202 should have beenreceived some time delay (X) earlier at time T_(A) at the first port104, where this time delay (X) is again associated with the processingdelay through the network device 102. A lookup time window (W) 114 isagain applied before performing a lookup operation 216 to compare theegress packet (PACKETB) 212 received at the second port 106 with packetsreceived at the first port 104, such as the packet (PACKETA) 202. Thelookup operation 216 is configured to determine whether or not theegress packet (PACKETB) 212 was previously received as an ingress packet(PACKETA) 202 at the first port 104. However, because packet (PACKETB)212 was an egress packet and only a single lookup window (W) 114 is usedto store packets, packet (PACKETA) 202 will no longer be stored whenlookup operation 216 is performed. As such, an additional lookupoperation 312 is also performed when the packet (PACKETB) 212 isreceived for this condition where the received packet is an egresspacket.

In contrast with embodiment 200, therefore, rather than using anextended lookup window 204 to account for egress packet conditions,additional lookup operations 302/312 are also performed when the packets202/212 are received. More particularly, the lookup operation 312 isconfigured to determine whether or not the egress packet (PACKETB) 212was previously received as an ingress packet (PACKETA) 202 at the firstport 104. Similarly, the additional lookup operation 302 is alsoperformed when the packet (PACKETA) 202 is received to handle the casein which this packet is an egress packet rather than an ingress packet.By applying lookup operations 302/312 when the packets 202/212 arereceived and by applying lookup operations 206/216 after the time window(W) 114, both ingress and egress conditions are handled by embodiment300.

It is noted that embodiment 200 of FIG. 2 and/or embodiment 300 of FIG.3 can be used to provide an indication of packets added, modified,and/or removed by the network device 102. However, as these embodiments200/300 do not track whether packets are ingress or egress packets,these embodiments 200/300 are not able to determine whether differencesrepresent removed packets or added/modified packets. To provide such adetermination, additional information can be added or tagged to thepackets and/or tracked with respect to the packets as they arrive toindicate whether they are ingress or egress packets. Further, thetraffic differentiator system 112 could utilize ports configured only toreceive ingress or egress packets from ports on the network device 102so that it would be known whether a received packet were an ingresspacket or an egress packet for the network device 102. As indicatedabove, ingress packets received on one port but not received as egresspackets on another port for the network device 102 can be deemed to bepackets removed by the network device 102. Similarly, egress packetsreceived on one port but not received as ingress packets on another portfor the network device 102 can be deemed to be packets added or modifiedby the network device 102. Further, additional processing can be appliedto determine additional statistical information about the packets beingremoved, added, and/or modified by the network device 102. Othervariations could also be implemented, as desired, while still utilizingthe packet stream difference processing techniques and lookup timewindows described herein.

FIGS. 4A-B and 5 are now discussed. These drawings provide exampleembodiments for the packet difference processor 120. The embodiments ofFIGS. 4A-B assume that the packet streams can include ingress and egresspackets. The embodiment of FIG. 5 assumes that one input packet streamincludes ingress packets and the other input packet stream includesegress packets.

FIG. 4A is a block diagram of an example embodiment for packetdifference processor 120 that is configured to determine differencesbetween ingress/egress packets received at two ports using two lookupoperations and a lookup time window. The blocks above dashed line 460represent processing associated with packets 401 received at a firstport (PORT1), and blocks below dashed line 460 represent processingassociated with packets 431 received at a second port (PORT2). Theembodiment depicted performs two lookup operations 402/406 with respectto the packets 401 for the first port (PORT1) and performs two lookupoperations 432/436 with respect to packets 431 for the second port(PORT2). The difference packets 408 represent ingress/egress packets 401received at the first port (PORT1) that were not within theingress/egress packets 431 received at the second port (PORT2).Similarly, the difference packets 438 represent ingress/egress packets431 received at the second port (PORT2) that were not within theingress/egress packets 401 received at the first port (PORT1). It isnoted that the lookup time window (W) 114 described above determines howlong packets and signature index values are stored within the buffers404/412/434/442, which are each described in more detail below.

Looking first to the processing above dashed line 460, lookup operation402 is performed on ingress/egress packets 401 from a first port(PORT1). Lookup operation 402 sends each packet to signature processor410. The signature processor 410 generates a signature for the packetand sends the signature to signature table 414 to add it to thesignatures stored in the signature table 414. The signature processor410 also sends to aging buffer 412 an index within the signature table414 for this signature, and this index is stored in aging buffer 412.The aging buffer 412 can be a first-in-first-out (FIFO) buffer or someother desired buffer that stores signature index values for a selectedamount of time associated with the lookup time window described herein.When a signature index leaves the aging buffer 412, that index isprovided to signature table 414 where it is used to delete the relatedsignature from the signature table 414. As such, the packet signaturesare stored for the lookup time window.

In addition to generating a signature and a signature index, thesignature processor 410 also communicates with the signature table 444for the second port (PORT2) to determine whether or not a signaturestored within the signature table 444 matches the signature generatedfor the received packet. This determination is then communicated tolookup operation 402 using a control message (CTRL) 418. If the controlmessage (CTRL) 418 indicates that a match was found, the lookupoperation 402 will drop the packet. If the control message (CTRL) 418indicates that a match was not found, the lookup processor 402 will passthe packet to packet buffer 404 where it is stored. The packet buffer404 can be a first-in-first-out (FIFO) buffer or some other buffer thatstores packets for a selected amount of time associated with the lookupwindow described herein. Once this lookup window has passed, the packetbuffer 404 sends the packet to lookup operation 406. As such, thepackets are stored for the lookup time window.

The lookup operation 406 sends each packet it receives from packetbuffer 404 to signature processor 420. The signature processor 420generates a signature for each packet and communicates with thesignature table 444 to determine whether or not a signature storedwithin the signature table 444 matches the signature generated for thepacket received from the packet buffer 404. This determination is thencommunicated to lookup operation 406 using a control message (CTRL) 424.If the control message (CTRL) 424 indicates that a match was found, thelookup operation 406 will drop the packet. If the control message (CTRL)424 indicates that a match was not found, the lookup processor 406 willoutput the packet as part of difference packets 408.

Looking now to the processing below dashed line 460, a lookup operation432 is performed with respect to the ingress/egress packets 431 from asecond port (PORT2). Lookup operation 432 sends each packet to signatureprocessor 440. The signature processor 440 generates a signature for thepacket and sends the signature to signature table 444 to add it to thesignatures stored in the signature table 444. The signature processor440 also sends to aging buffer 442 an index within the signature table444 for this signature, and this index is stored in aging buffer 442.The aging buffer 442 can be a first-in-first-out (FIFO) buffer or someother desired buffer that stores signature index values for a selectedamount of time associated with the lookup window described herein. Whena signature index leaves the aging buffer 442, that index is provided tosignature table 444 where it is used to delete the related signaturefrom the signature table 414. As such, the packet signatures are storedfor the lookup time window.

In addition to generating a signature and a signature index, thesignature processor 440 also communicates with the signature table 414for the first port (PORT1) to determine whether or not a signaturestored within the signature table 414 matches the signature generatedfor the received packet. This determination is then communicated tolookup operation 432 using a control message (CTRL) 448. If the controlmessage (CTRL) 448 indicates that a match was found, the lookupoperation 432 will drop the packet. If the control message (CTRL) 448indicates that a match was not found, the lookup processor 432 will passthe packet to packet buffer 434 where it is stored. The packet buffer434 can be a first-in-first-out (FIFO) buffer or some other buffer thatstores packets for a selected amount of time associated with the lookupwindow described herein. Once this lookup window has passed, the packetbuffer 434 sends the packet to lookup operation 436. As such, thepackets are stored for the lookup time window.

The lookup operation 436 sends each packet it receives from packetbuffer 434 to signature processor 450. The signature processor 450generates a signature for each packet and communicates with thesignature table 414 to determine whether or not a signature storedwithin the signature table 414 matches the signature generated for thepacket received from the packet buffer 434. This determination is thencommunicated to lookup operation 436 using a control message (CTRL) 454.If the control message (CTRL) 454 indicates that a match was found, thelookup operation 436 will drop the packet. If the control message (CTRL)454 indicates that a match was not found, the lookup processor 436 willoutput the packet as part of difference packets 438.

It is noted that the difference packets 408 and the difference packets438 can then be combined to form a single difference packet output. Thepacket contents for the difference packets 408/438 can also be analyzedto provide additional statistical information concerning the differencepackets, as desired. It is further noted that the signature processors410/420/440/450 can use a variety of techniques to generate signaturesfor received packets. For example, one or more hash algorithms can beapplied to contents of received packets to generate signatures for thereceived packets. Further, the signature can be calculated using thefull contents of the packet or using only select portions of the packetcontents, as desired. Using only selected portions of the packetcontents allows for one or more packet modifications that are done bythe network device 102 to be ignored in the difference determinationoperations. As such, packets can still be detected as non-differentcopies of each other even though certain fields may have been updated ormodified by the network device 102. For example, where the networkdevice 102 updates the time-to-live (TTL) field within an IP (internetprotocol) packet, adds/removes a VLAN (virtual local area network) tagwithin a packet, and/or performs other modifications to the packets,these packet modifications can be ignored in the difference processingby generating signatures that do not consider these portions of thepacket. As described above, the signature is added to the signaturetables 414/444, and the index to the signature is added to the agingbuffers 412/432. Other signature generation techniques could also beutilized, if desired.

In operation, the embodiment of FIG. 4A will detect removed, modified,and/or added packets between the two ports (PORT1/PORT2) within acertain lookup time window. This lookup time window is determined by theamount of time selected for the packet buffers 404/434 to store packetsand for the aging buffers 412/442 to store signature index values. Thepacket difference processor 120 will detect if a packet is present inboth streams as long as the time between the packets is less than thesize selected for the lookup time window. As such, packets not withinboth streams for the ports (PORT1/PORT2) will be output as differencepackets, as well as packets that are within both streams but are notreceived at the ports within the lookup time window.

It is further noted that the packet streams received by the ports(PORT1/PORT2) for the traffic differentiator system 112 could beassociated with different network devices and/or sources, if desired.Further, the packet streams being received could be packets streams thathave been aggregated from one or more ports/sources. In short, while thetraffic differentiator system 112 is useful for comparing differencesbetween packets received by a network device 102 and packets output bythat network device 102, the traffic differentiator system 112 can beused to determine difference between any desired packet streams providedto the traffic differentiator system 112.

As indicated above, the lookup time window can be selected based uponthe expected processing time it takes for a packet to travel through thenetwork device 102. The size of buffers 404/412/434/442 and thesignature tables 414/444 will be dependent upon the amount of timeselected for the lookup window. Larger amounts of time will requirelarger buffers and tables, while smaller amounts of time will requiresmaller buffers and tables. It is noted that the buffers and tables canbe implemented using any desired programmable storage medium, such asrandom access memory (RAM), FLASH memory, and/or other programmable datastorage mediums.

It is further noted that one or more packet filters 405 and 435 can alsobe used, for example prior to lookup operations 402 and 432, and can beconfigured to remove packets that are not desired to be consideredwithin the difference processing. For example, these packet filters405/435 can be used to drop packets having predefined packet types, suchas for example packets generated inside the network device 102 that arenot of significance. The packet filters 405/435, therefore, can be usedto mask selected packets from the difference processing. While thepacket filters 405/435 are shown as being in front of lookup operations402 and 432, packet filters could also be placed in different locationsand additional packet filters could be utilized. It is noted that thefilters 405/435 can apply one or more filter rules to determine whetheror not to pass or drop received packets.

FIG. 4B is a block diagram of an example embodiment for packetdifference processor 120 that is configured to determine differencesbetween ingress/egress packets received at two ports using one lookupoperation and an extended lookup time window. As described above withrespect to embodiment 200 of FIG. 2, the number of lookup operationsused by packet difference processor 120 can be reduced if the timelookup window is extended. In such a configuration, for example, thelookup time window (W) 114 can be doubled by adding extended lookup timewindow (W) 204 to make the overall window twice as long (2W). With thislonger time window, only a single lookup operation 406 is then used withrespect to packets 401 from PORT1, and the lookup operation 402 isremoved. As such, the packets 402 from PORT1 are provided directly topacket buffer 404 and to signature processor 410, and no lookupoperation to signature table 444 is conducted by signature processor410. Similarly, only a single lookup operation 436 is used with respectto packets 431 from PORT2, and the lookup operation 432 is removed. Assuch, the packets 431 from PORT2 are provided directly to packet buffer434 and to signature processor 440, and no lookup to signature table 414is conducted by signature processor 440. While extending the lookup timewindow reduces the number of lookup operations, this configuration wouldessentially require doubling of the sizes for the buffers404/412/434/442 and tables 414/444 as these buffers and tables will bestoring twice as many packets, index values, and signatures.

The packet difference processor 120 can be streamlined if ports(PORT1/PORT2) are dedicated to receive ingress or egress packets ratherbeing configured to received both ingress and egress packets. In such aconfiguration, a port that receives only egress packets does not need tostore packets in a packet buffer because any duplicate ingress packetwill always be received before its related egress packet. Conversely, aport that receives only ingress packets does not have to do a lookupoperation before the packet buffer because any duplicate egress packetwill always be received after its related ingress packet.

FIG. 5 is a block diagram of an example embodiment for packet differenceprocessor 120 where the ports (PORT1/PORT2) receive only ingress packetsor only egress packets. The blocks above dashed line 560 representprocessing associated with ingress only packets 501 received at a firstport (PORT1), and blocks below dashed line 560 represent processingassociated with egress only packets 531 received at a second port(PORT2). The embodiment depicted performs one lookup operation 406 withrespect to the packets 501 and performs one lookup operation 432 withrespect to packets 531. The removed packets 508 represent ingresspackets 501 received at the first port (PORT1) that were not within theegress packets 531 received at the second port (PORT2). The addedpackets 538 represent egress packets 531 received at the second port(PORT2) that were not within the ingress packets 501 received at thefirst port (PORT1). It is noted that the lookup time window (W) 114described above determines how long packets and signature values arestored within the buffers 404/412/442.

Looking first to the processing above dashed line 560, ingress packets501 from a first port (PORT1) are provided directly to packet buffer 404and signature processor 410. As with FIGS. 4A-B, the signature processor410 generates a signature for the packet and sends the signature tosignature table 414 to add it to the signatures stored in the signaturetable 414. The signature processor 410 also sends to aging buffer 412 anindex within the signature table 414 for this signature, and this indexis stored in aging buffer 412. When a signature index leaves the agingbuffer 412, that index is provided to signature table 414 where it isused to delete the related signature from the signature table 414.

Unlike the embodiment of FIG. 4A but like the embodiment of FIG. 4B,there is no lookup operation positioned in front of packet buffer 404.Rather, all ingress packets 501 are stored within packet buffer 404 foran amount of time determined by the lookup time window 114 describedherein. Once this lookup time window (W) 114 has passed, the packetbuffer 404 sends the packet to lookup operation 406.

As with FIGS. 4A-B, the lookup operation 406 sends each packet itreceives from packet buffer 404 to signature processor 420. Thesignature processor 420 generates a signature for each packet andcommunicates with the signature table 444 to determine whether or not asignature stored within the signature table 444 matches the signaturegenerated for the packet received from the packet buffer 404. Thisdetermination is then communicated to lookup operation 406 using acontrol message (CTRL) 424. If the control message (CTRL) 424 indicatesthat a match was found, the lookup operation 406 will drop the packet.If the control message (CTRL) 424 indicates that a match was not found,the lookup processor 406 will output the packet as part of removedpackets 508.

Looking now to the processing below dashed line 560, egress packets 531from a second port (PORT2) are sent to lookup operation 432. Lookupoperation 432 sends each packet to signature processor 440. Thesignature processor 440 generates a signature for the packet and sendsthe signature to signature table 444 to add it to the signatures storedin the signature table 444. The signature processor 440 also sends toaging buffer 442 an index within the signature table 444 for thissignature, and this index is stored in aging buffer 442. When asignature index leaves the aging buffer 442 after it has been stored forthe lookup time window 114, that index is provided to signature table444 where it is used to delete the related signature from the signaturetable 414.

As with FIG. 4A but not with FIG. 4B, in addition to generating asignature and a signature index, the signature processor 440 alsocommunicates with the signature table 414 for the first port (PORT1) todetermine whether or not a signature stored within the signature table414 matches the signature generated for the received packet. Thisdetermination is then communicated to lookup operation 432 using acontrol message (CTRL) 448. If the control message (CTRL) 448 indicatesthat a match was found, the lookup operation 432 will drop the packet.If the control message (CTRL) 448 indicates that a match was not found,the lookup processor 432 will pass the packet. Unlike the embodiment ofFIG. 4A, there is no buffer or lookup operation positioned after lookupoperation 432 in the embodiment of FIG. 5. Rather, all passed packetsfrom lookup operation 432 are output as added or modified packets 538.

In operation, the embodiment of FIG. 5 will detect packets removed oradded/modified by network device 102 between the first ingress ports(PORT1) and the second egress port (PORT2) within a certain lookup timewindow. As indicated above, this lookup time window determines how longthe packet buffer 404 will store ingress packets and how long the agingbuffers 412/442 will store signature index values. The packet differentprocessor 120 will detect if a packet is present in both ingress andegress streams as long as the time between the packets is less than thesize selected for the lookup time window. As such, packets within astream for one port but not in the stream for another port (e.g.,received at PORT1 but not PORT2 or vice versa) will be output asdifference packets, as well as packets that are within both streams butare not received at the egress port (PORT2) within the lookup timewindow after being received at the ingress port (PORT1).

As indicated above, the lookup time window 114 can be selected basedupon the expected processing time it takes for a packet to travelthrough the network device 102. As also indicated above, the size ofbuffers 404/412/442 and the signature tables 414/444 will be dependentupon the amount of time selected for the lookup time window. Largeramounts of time will require larger buffers and tables, while smalleramounts of time will require smaller buffers and tables. It is againnoted that the buffers and tables can be implemented using any desiredprogrammable storage medium, such as random access memory (RAM), FLASHmemory, and/or other programmable data storage mediums. It is also againnoted that packet filters and associated filter rules could also be usedto further filter packets to be processed, if desired.

FIGS. 6-7 are now discussed and provide example embodiments where thepacket differentiator system 112 is used to provide differenceprocessing for larger numbers of input streams. In addition todetermining differences between packet streams received at two ports108/110 for a network device 102, the packet differentiator system 112can also be used to determine differences among packet streams receivedat more than two ports for the packet differentiator system 112. In suchconfigurations, the lookup operations associated with packets receivedat one port can be configured to communicate with signature tables fortwo or more other ports to determine if matches exist for packetsreceived at those additional ports. For the discussions of FIGS. 6-7below, it is assumed that each input packet stream received at a portfor the packet differentiator system 112 is associated with a particularport on a network device 102. However, as described herein, the inputpacket streams can also be from multiple network devices and/or sources,and the packet streams can further represent an aggregation of multiplepacket streams. Other variations could also be implemented while stillutilizing the lookup time window and difference processing techniquesdescribed herein.

The number of lookup operations performed by the packet differenceprocessor 120 for embodiments according to FIGS. 6-7 that are applied tolarger numbers of packet streams can be configured to be proportional tothe number of ports and can be determined by the type of packets beingreceived at the ports and the difference determinations desired to bemade. For example, the number of lookups can be 2*(P−1) using the portprocessing shown in embodiment FIG. 4B where two lookups are used withrespect to each port and where P is the total number of ports. Asdescribed above, the number of lookups can be reduced to a single lookupper port if the lookup time window is extended (e.g., doubling the timewindow). For example, the number of lookups can be P−1 using the portprocessing shown in embodiment FIG. 4A where an extended lookup timewindow is used along with a single lookup per port. As described abovewith respect to FIG. 5, the number of lookups can also be reduced byusing ports that receive only ingress packets or that receive onlyegress packets. For such configurations, ingress port lookups need onlybe made to egress port signature tables, and egress port lookups needonly be made to ingress port signature tables. Thus, the number oflookups can be reduced to P/2 using the port processing shown in FIG. 5where one lookup is used with respect to each port and where P is thetotal number of ports split between ingress and egress ports. Othervariations could also be implemented while still utilizing the lookuptime window and difference processing techniques described herein.

FIG. 6 is a block diagram of an embodiment 600 for using a trafficdifferentiator system 112 to determine differences between a pluralityof ingress ports 604 and a plurality of egress ports 606 for a networkdevice 102. For this embodiment, network device 102 includes N ingressports 604 that receive ingress packets 601, and copies for these ingresspacket streams are received at N ports 609 for traffic differentiatorsystem 112 as N ingress packet streams 608. Network device 102 alsoincludes N egress ports 606 that receive and output egress packets 602,and copies for these egress packets are received at N ports 611 fortraffic differentiator system 112 as N egress packet streams 610. Forthis embodiment 600, the traffic differentiator system 112 determinesdifferences between ingress packet streams and egress packet streamsusing the packet difference processor 120. The results of thisdifference processing can include difference packets 122 and/or otherdesired information 124 related to the difference processing or thedifference packets.

FIG. 7 is a block diagram of an embodiment 700 where two ingress portsand two egress ports for the traffic differentiator system 112 are beingprocessed within a packet difference processor (PDP) 120 for the trafficdifferentiator system 112. A lookup operation 432A is applied to packetsreceived from an egress port (PORT2), and this lookup operation 432Acommunicates with signature tables associated with the two ingress ports(PORT1, PORT3) as represented by the arrows. Similarly, a lookupoperation 432B is applied to packets received from the other egress port(PORT4), and this lookup operation 432B would also communicate withsignature tables associated with the two ingress ports (PORT1, PORT3) asrepresented by the arrows. As also depicted, a lookup operation 406A isapplied to packets received from an ingress port (PORT1), and thislookup operation 406A communicates with signature tables associated withthe two egress ports (PORT2, PORT4) as represented by the arrows.Similarly, a lookup operation 406B is applied to packets received fromthe other ingress port (PORT3), and this lookup operation 406Bcommunicates with signature tables associated with the two egress ports(PORT2, PORT4) as represented by the arrows. It is noted that otheroperational blocks as described above with respect to FIGS. 4A-B and 5could also be utilized with respect to the dedicated ingress and egressports. Further, as described above, the results of the differenceprocessing can be added/modified packets 738 and dropped packets 708.

FIGS. 8-9 are now discussed and provide example embodiments where twopackets streams, such as an ingress packet stream and an egress packetstream, are combined into a combined packet stream before beingprocessed by a packet difference processor 120 for a trafficdifferentiator system 112. The combined packet stream can be received atan input port for the traffic differentiator system 112, or the packetstreams can be combined within the traffic differentiator system 112.The packet streams can be combined by interleaving the two packetstreams and/or using other desired aggregation techniques. Othervariations can also be implemented.

Looking first to FIG. 8, a block diagram is provided of an exampleembodiment 800 where the traffic differentiator system 112 receivescombined packets 804 at input port (PORT1) 104. For the embodiment 800depicted, the network device 102 is configured to receive ingresspackets and to output processed versions of these packets as egresspackets using a packet processor 103. The traffic differentiator system112 is configured to receive the combined packets 804 at the first port104. Copies of the ingress packets 108 and copies of the egress packets110 are combined by combiner 802 to form the combined packets 804. Asdescribed herein, the traffic differentiator system 112 determinesdifferences between packet streams using the packet difference processor120 and the lookup time window 114. The resulting difference packets 122are output by the traffic differentiator system 112. The trafficdifferentiator system 112 can also be configured to output otherinformation 124 related to the difference processing and differencepackets, such as statistical information about the difference packets.Although combiner 802 is shown outside the traffic differentiatorsystem, it is noted that ingress/egress packet streams 108/110 could bereceived at different ports for the traffic differentiator system 112and could then be combined within the traffic differentiator system 112prior to processing by the packet difference processor 120, if desired.Other variations could also be implemented.

FIG. 9 is a block diagram of an example embodiment for processingcombined packets 904 with a packet difference processor 120 for atraffic differentiator system 112. For the embodiment depicted, twolookup operations 902/906 are performed with respect to the combinedpackets 904. The difference packets 908 represent packets within thecombined packets 904 that are detected to be received only once in thecombined packets 904 within a time window (W) 114. As described herein,the lookup time window (W) 114 determines how long packets and signatureindex values are stored within the buffers 404/412, which are eachdescribed in more detail below. It is further noted that for theembodiment of FIG. 9 applied to a network device 102, it is preferablethat each ingress packet is received only once by the network device 102and that each egress packet is output only once by the network device102. Thus, when these ingress/egress packets are combined to form thecombined packets 904 that are processed by the packet differenceprocessor 120 depicted in FIG. 9, each ingress packet and each egresspacket will occur only once within the combined packets 904 within thetime window unless they represent packets added, dropped, or modified bythe network device 102. These added/dropped/modified packets are outputas difference packets 908 by the embodiment of FIG. 9.

Looking back to FIG. 9, lookup operation 902 is first performed onreceived packets within combined packets 904, and each received packetis sent to signature processor 910. The signature processor 910generates a signature for the packet and sends the signature tosignature table 414 to add it to the signatures stored in the signaturetable 414. The signature processor 910 also sends to aging buffer 412 anindex within the signature table 414 for this signature, and this indexis stored in aging buffer 412. The aging buffer 412 can be afirst-in-first-out (FIFO) buffer or some other desired buffer thatstores signature index values for a selected amount of time associatedwith the lookup time window described herein. When a signature indexleaves the aging buffer 412, that index is provided to signature table414 where it is used to delete the related signature from the signaturetable 414. As such, the packet signatures are stored for the lookup timewindow.

In addition to generating a signature and a signature index, thesignature processor 910 also communicates with the signature table 414to determine whether or not a signature stored within the signaturetable 414 matches the signature generated for the received packet. Thisdetermination is then communicated to lookup operation 902 using acontrol message (CTRL) 918. If the control message (CTRL) 918 indicatesthat a match was found, the lookup operation 902 will drop the packet sothat it is not stored in the packet buffer 404, although the signatureand index for this matched packet is still stored in the signature table414 and aging buffer 412, as indicated above. If the control message(CTRL) 918 indicates that a match was not found, the lookup processor902 will pass the packet to packet buffer 404 where it is stored. Thepacket buffer 404 can be a first-in-first-out (FIFO) buffer or someother buffer that stores packets for a selected amount of timeassociated with the lookup window described herein. Once this lookupwindow has passed, the packet buffer 404 sends the packet to lookupoperation 906. As such, the packets are stored for the lookup timewindow. Further, as described above, after the lookup time window passesand the packet leaves the packet buffer 404, the index for the packetsignature stored within the aging buffer 412 and the packet signaturestored within the signature table 412 for the packet are also bothremoved, as the lookup time window will have passed.

The lookup operation 906 sends each packet it receives from packetbuffer 404 to signature processor 920. The signature processor 920generates a signature for each packet and communicates with thesignature table 414 to determine whether or not a signature storedwithin the signature table 414 matches the signature generated for thepacket received from the packet buffer 404. This determination is thencommunicated to lookup operation 906 using a control message (CTRL) 924.If the control message (CTRL) 924 indicates that a match was found, thelookup operation 906 will drop the packet. If the control message (CTRL)924 indicates that a match was not found, the lookup processor 906 willoutput the packet as part of difference packets 908. As indicated above,the difference packets 908 represent packets that occur only once withinthe combined packets 904 within the lookup time window. For example, ifan ingress packet and a matching egress packet are received within thelookup time window, a match will be found for the ingress packet and amatch will also be found for the egress packet through the lookupoperations. In particular, for the later received egress packet, lookupoperation 902 will find the packet signature for the ingress packetwithin signature table 414 that matches the egress packet signature. Asthe egress packet is not stored in the packet buffer 404 once a match isfound by lookup operation 902, lookup operation 906 is not performed onthe egress packet although the egress packet signature and the relatedindex are still stored in the signature table 414 and aging buffer 412,as described above. For the earlier received ingress packet, lookupoperation 906 will find this packet signature for the egress packetwithin signature table 414 that matches the ingress packet signature. Asthe packet signature for the ingress packet is removed once its indexages out of the aging buffer 412 and the ingress packet is released fromthe packet buffer 404 after the lookup time window has passed, lookupoperation 906 will not find a match to the ingress packet signatureitself.

It is again noted that the packet contents for the difference packets908 can be analyzed to provide additional statistical informationconcerning the difference packets, as desired. Further, as describedabove, the signature processors 910/920 can use a variety of techniquesto generate signatures for received packets. For example, one or morehash algorithms can be applied to contents of received packets togenerate signatures for the received packets. Further, the signature canbe calculated using the full contents of the packet or using only selectportions of the packet contents, as desired. Using only selectedportions of the packet contents allows for one or more packetmodifications that are done by the network device 102 to be ignored inthe difference determination operations. As such, packets can still bedetected as non-different copies of each other even though certainfields may have been updated or modified by the network device 102. Forexample, where the network device 102 updates the time-to-live (TTL)field within an IP (internet protocol) packet, adds/removes a VLAN(virtual local area network) tag within a packet, and/or performs othermodifications to the packets, these packet modifications can be ignoredin the difference processing by generating signatures that do notconsider these portions of the packet. As described above, the signatureis added to the signature table 414, and the index to the signature isadded to the aging buffers 412. Other signature generation techniquescould also be utilized, if desired.

In operation, the embodiment of FIG. 9 will detect difference packets908 that represent packets received only once within the combinedpackets 904 within a certain lookup time window. This lookup time windowis determined by the amount of time selected for the packet buffer 404to store packets and for the aging buffer 412 to store signature indexvalues. As also indicated above, the lookup time window can be selectedbased upon the expected processing time it takes for a packet to travelthrough and/or be processed by the network device 102 where packetsentering one or more ports and leaving one or more ports on the networkdevice 102 are combined to form the combined packets 904. The size ofbuffer 404/412 and the signature table 414 will be dependent upon theamount of time selected for the lookup window. Larger amounts of timewill require larger buffers and tables, while smaller amounts of timewill require smaller buffers and tables. It is noted that the buffersand tables can be implemented using any desired programmable storagemedium, such as random access memory (RAM), FLASH memory, and/or otherprogrammable data storage mediums.

As above, it is further noted that one or more packet filters 405 canalso be used, for example prior to lookup operation 902, and can beconfigured to remove packets that are not desired to be consideredwithin the difference processing. For example, the packet filter 405 canbe used to drop packets having predefined packet types, such as forexample packets generated inside the network device 102 that are not ofsignificance. The packet filter 405, therefore, can be used to maskselected packets from the difference processing. While the packet filter405 is shown as being in front of lookup operation 902, a packet filtercould also be placed in different locations and additional packetfilters could be utilized. As described above, the filters can apply oneor more filter rules to determine whether or not to pass or dropreceived packets.

It is again noted that the ports or sources from which packets arereceived by the traffic differentiator system 112 could be associatedwith different network devices, if desired. Further, the packet streamsbeing received could be packets streams that have been aggregated fromone or more ports/sources. In short, while the traffic differentiatorsystem 112 is useful for comparing differences between packets receivedby a network device 102 and packets output by that network device 102,the traffic differentiator system 112 can be used to determinedifference packets between any desired packet streams provided to thetraffic differentiator system 112 and within a single packet streamprovided to the traffic differentiator system 112.

As indicated above, to facilitate the difference processing and toprovide additional difference information associated with receivedpacket streams, the traffic differentiator system 112 can also beconfigured to tag received packets with additional information and/or tocount numbers of packets. For example, where the network device is aload balancer system, it is desirable to determine that each packetwithin a received ingress packet stream is only output once to aplurality of different received egress packet streams. Further, wherethe network device is a multi-casting system it is desirable todetermine that each packet within a received ingress packet stream isoutput a selected number of times depending upon the number of egressstreams being generated by the multicast processing. By tagging thereceived packets with port information and then tracking this portinformation along with counting the number of times particular packetsare received, the traffic differentiator system 112 can providedeterminations for load balancer systems, multi-casting systems, and/orother types of network devices. Other variations could also beimplemented while still utilizing the lookup time window and differenceprocessing techniques described herein.

It is also noted that the operational blocks described herein can beimplemented using hardware, software or a combination of hardware andsoftware, as desired. In addition, integrated circuits, discretecircuits or a combination of discrete and integrated circuits can beused, as desired, that are configured to perform the functionalitydescribed. Further, programmable integrated circuitry can also be used,such as FPGAs (field programmable gate arrays), ASICs (applicationspecific integrated circuits), and/or other programmable integratedcircuitry. In addition, one or more processors running software orfirmware could also be used, as desired. For example, computer readableinstructions embodied in a tangible medium (e.g., memory storagedevices, FLASH memory, random access memory, read only memory,programmable memory devices, reprogrammable storage devices, harddrives, floppy disks, DVDs, CD-ROMs, and/or any other tangible storagemedium) could be utilized including instructions that cause computersystems, programmable circuitry (e.g., FPGAs), and/or processors toperform the processes, functions, and capabilities described herein. Itis further understood, therefore, that one or more of the tasks,functions, or methodologies described herein may be implemented, forexample, as software or firmware and/or other instructions embodied inone or more non-transitory tangible computer readable mediums that areexecuted by a CPU, controller, microcontroller, processor,microprocessor, or other suitable processing circuitry.

Further modifications and alternative embodiments of this invention willbe apparent to those skilled in the art in view of this description. Itwill be recognized, therefore, that the present invention is not limitedby these example arrangements. Accordingly, this description is to beconstrued as illustrative only and is for the purpose of teaching thoseskilled in the art the manner of carrying out the invention. It is to beunderstood that the forms of the invention herein shown and describedare to be taken as the presently preferred embodiments. Various changesmay be made in the implementations and architectures. For example,equivalent elements may be substituted for those illustrated anddescribed herein, and certain features of the invention may be utilizedindependently of the use of other features, all as would be apparent toone skilled in the art after having the benefit of this description ofthe invention.

What is claimed is:
 1. A traffic differentiator system for networkpackets, comprising: a packet difference processor configured todetermine difference packets within a lookup time window between a firststream of packets and a second stream of packets received by the trafficdifferentiator system, the second stream of packets representing aprocessed version of the first stream of packets, and the lookup timewindow being associated with a processing time for the second stream tobe a processed version of the first stream; and at least one output portconfigured to output the difference packets, the difference packetscomprising packets present in only one of the first and second streamswithin the lookup time window so as to include only packets within thefirst stream and not within the second stream and packets within thesecond stream and not within the first stream.
 2. The trafficdifferentiator system of claim 1, wherein the packet differenceprocessor is further configured to output statistical information aboutthe difference packets.
 3. The traffic differentiator system of claim 1,further comprising: at least one input port configured to receive thefirst stream of packets; and at least one additional input portconfigured to receive the second stream of packets.
 4. The trafficdifferentiator system of claim 3, wherein the first and second streamsof packets are from a single network device.
 5. The trafficdifferentiator system of claim 4, wherein the first stream of packetsincludes only ingress packets for the network device and the secondstream of packets includes only egress packets for the network device.6. The traffic differentiator system of claim 4, wherein the differencepackets represent at least one of packets removed by the network device,packets added by the network device, or packets modified by the networkdevice.
 7. The traffic differentiator system of claim 3, furthercomprising: a packet signature generator associated with each input portand configured to generate a signature for each of a plurality ofpackets received at the input port; and a signature table associatedwith each input port and configured to store the signatures, thesignature tables being configured to store signatures for the lookuptime window.
 8. The traffic differentiator system of claim 7, whereinthe packet difference processor is further configured to perform foreach input port at least one lookup between signatures generated for thepackets received at that input port and the signature table associatedwith at least one other input port and to drop packets where matches arefound.
 9. The traffic differentiator system of claim 8, wherein thepacket difference processor is configured to perform two lookupsassociated with each input port, and wherein a packet buffer storespackets between the two lookups.
 10. The traffic differentiator systemof claim 8, wherein the packet difference processor performs one lookupassociated with each input port, and wherein a packet buffer storespackets before the lookup.
 11. The traffic differentiator system ofclaim 8, wherein the input ports are configured to receive ingresspackets or egress packets but not both, wherein the packet differenceprocessor is configured to perform one lookup associated with each inputport, and wherein a packet buffer stores packets for each input portconfigured to receive ingress packets.
 12. The traffic differentiatorsystem of claim 3, further comprising one or more packet filtersassociated with the input ports and configured to drop or pass packetsbased upon filter rules.
 13. The traffic differentiator system of claim1, wherein the first stream of packet includes only ingress packetsassociated with a network device, and wherein the second packet streamincludes only egress packets associated with the network device.
 14. Thetraffic differentiator system of claim 13, wherein the packet differenceprocessor is configured to receive a combined packet stream includingthe first stream of ingress packets and the second stream of egresspackets.
 15. The traffic differentiator system of claim 14, furthercomprising an input port configured to receive the combined packetstream.
 16. The traffic differentiator system of claim 15, furthercomprising: a packet signature generator configured to generate asignature for each of a plurality of packets received at the input port;and a signature table configured to store signatures for the lookup timewindow.
 17. The traffic differentiator system of claim 16, wherein thepacket difference processor is configured to perform two lookupsassociated with the input port and to drop packets where matches arefound, and wherein a packet buffer stores packets between the twolookups.
 18. The traffic differentiator system of claim 15, furthercomprising one or more packet filters associated with the input port andconfigured to drop or pass packets based upon filter rules.
 19. A methodfor generating difference packets between streams of network packets,comprising: determining difference packets within a lookup time windowbetween a first stream of packets and a second stream of packetsreceived by a traffic differentiator system, the second stream ofpackets representing a processed version of the first stream of packets,and the lookup time window being associated with a processing time forthe second stream to be a processed version of the first stream; andoutputting the difference packets, the difference packets comprisingpackets present in only one of the first and second streams within thelookup time window so as to include only packets within the first streamand not within the second stream and packets within the second streamand not within the first stream.
 20. The method of claim 19, furthercomprising outputting statistical information about the differencepackets.
 21. The method of claim 19, further comprising: receiving thefirst stream of packets with at least one input port for the packetdifferentiator system; and receiving the second stream of packets withat least one additional input port for the packet differentiator system.22. The method of claim 21, wherein the first and second streams ofpackets are received from a single network device.
 23. The method ofclaim 22, wherein the first stream of packets include only ingresspackets for the network device and the second stream of packets includesonly egress packets for the network device.
 24. The method of claim 22,wherein the difference packets represent at least one of packets removedby the network device, packets added by the network device, or packetsmodified by the network device.
 25. The method of claim 21, wherein thedetermining step comprises: generating a signature for each of aplurality of packets received at the input ports; storing the signaturesfor the lookup time window; and comparing signatures to determinedifference packets.
 26. The method of claim 25, further comprisingperforming for each input port at least one lookup between signaturesgenerated for the packets received at that input port and signaturesstored for at least one other input port and dropping packets wherematches are found.
 27. The method of claim 26, wherein two lookups areperformed for each input port, and further comprising storing packetsbetween the two lookups.
 28. The method of claim 26, wherein one lookupis performed for each input port, and further comprising storing packetsbefore the lookup.
 29. The method of claim 26, wherein the input portsare configured to receive ingress packets or egress packets but notboth, wherein a lookup is performed at each input port for each otherinput port, and further comprising storing packets for each input portreceiving ingress packets.
 30. The method of claim 21, furthercomprising applying one or more packet filters to drop or pass packetsbased upon filter rules.
 31. The method of claim 19, wherein the firststream of packet includes only ingress packets associated with a networkdevice, and wherein the second packet stream includes only egresspackets associated with the network device.
 32. The method of claim 31,wherein the first stream of ingress packets and the second stream ofegress packets are combined to form a combined packet stream.
 33. Themethod of claim 32, further comprising receiving the combined packetstream at an input port for the packet differentiator system.
 34. Themethod of claim 33, wherein the determining step comprises: generating asignature for each of a plurality of packets received at the input port;storing the signatures for the lookup time window; and comparingsignatures to determine difference packets.
 35. The method of claim 34,further comprising performing two lookups between signatures generatedfor the packets received at the input port and stored signatures, anddropping packets where matches are found.
 36. The method of claim 33,further applying one or more packet filters to drop or pass packetsbased upon filter rules.